Compositions and methods for inhibiting or inducing adipogenesis

ABSTRACT

This invention relates generally to compositions and methods which utilization nuclear receptors for regulating adipogenesis in cells. Specifically, the invention is directed to compositions which regulate transcription factor PPARγ and enhance or inhibit the transcription of genes responsible for directing cell differentiation towards a pathway of adipogenesis. More specifically, disclosed herein is a novel polypeptide coactivator of PPARγ, and fragments thereof, which possess coactivator or corepressor activity. Also related are nucleotide sequences which express these polypeptides. Also disclosed is an interfering RNA that may be used to inhibit adipogenesis.

RELATED APPLICATIONS

This patent application claims priority from U.S. provisional patentapplication Ser. No. 60/851,156, filed Oct. 12, 2006, which isincorporated herein by reference in its entirety.

GOVERNMENT SUPPORT CLAUSE

This work was supported by the National Institutes of Health GrantNumber HL075755. The U.S. Government has certain rights in thisinvention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to compositions and methods ofregulating adipogenesis in cells. Specifically, the invention isdirected to the utilization of nuclear receptors and their cofactorsincluding PPARγ. Also related are polypeptides that enhance or inhibitPPARγ activation and the subsequently the transcription of genesresponsible for adipogenesis. Also related are nucleotide sequenceswhich express these polypeptides.

2. Description of the Related Art

Obesity, defined as a state of pathologically excessive adipose tissuemass, has been identified as an epidemic in the U.S. for more than twodecades. Yet the numbers of overweight and obese adults and childrencontinues to rise. Currently, the rates of both overweight and obesityin the U.S. are 61 percent and 14 percent in adults and children,respectively. Among U.S. adults aged 20-74 years, the prevalence ofoverweight (defined as BMI 25.0-29.9) has increased from 33 percent in1980 to 35 percent of the population in 1999. The disease is associatedwith several serious health conditions including type 2 diabetesmellitus, heart disease, high blood pressure and stroke. It is alsolinked to higher rates of certain types of cancer. Obesity is anindependent risk factor for heart disease, hypoxia, sleep apnea, hernia,and arthritis. Obesity is the seventh leading cause of death in the U.S.The total cost of obesity and related conditions by some estimates is$100 billion annually.

The development of obesity requires the continuous differentiation ofnew adipocytes throughout life, and this process of adipocytedifferentiation from preadipocytes is called adipogenesis. Many studieshave demonstrated the importance of transcription factors, especiallynuclear receptors (NRs) and their coactivators, in adipocyteproliferation, gene expression regulation, and differentiation.

Nuclear receptors are a superfamily of transcription factors (TFs) thatregulate the expression of target genes in response to steroid hormonesand other ligands. To date, there are 48 NRs reported and each playsdistinct or interrelated functions (Ruan et al. (2005) KidneyInternational 68, 2444-2461). However, recent studies have demonstratedthat NR functions are modulated by a large group of proteins calledcoregulators. These coregulators include coactivators which promotetranscription and corepressors which attenuate promoter activity whenrecruited into the promoter regions of specific genes (McKenna andO'Malley (2002) Endocrinology 143, 2461-2465; Glass (2006) J. Clin.Invest. 116, 556-560; Aranda and Pascual (2001) Physiol. Rev. 81,1269-1304; McKenna and O'Malley (2002) Cell 108, 465-474; Smith andO'Malley (2004) Endocr Rev 25, 45-71; Darimont et al. (1998) Genes Dev.12, 3343-3356; Xu (2005) Biochem Cell Biol 83, 418-428; O'Malley (2003)Nucl Recept Signal 1, e010; Lee et al. (2001) Cell Mol Life Sci 58,289-297; Robyr et al. (2000) Molecular Endocrinology 14, 329-347).

Regulation of adipogenesis is central to conditions of overweight andunderweight. Adipogenesis is a multistage process that includesexpression of a complex set of transcription factors that initiatetranscription of preadipocyte- or adipocyte-specific genes. Thistranscriptional cascade includes expression of key adipogenesisregulators, such as PPARs, CCAAT/enhancer binding protein (C/EBP), andthe basic helix-loop-helix (bHLH) family of transcription factors suchas ADD1/SREBP1c (Rosen et al. (2000) Genes Dev. 14, 1293-1307). Thesetranscription factors activate genes encoding enzymes that are involvedin lipid storage and transport such as adipocyte-specific fatty acidbinding protein (aP2) and perilipin, and genes encoding secretedproteins or adipokines that modulate preadipocyte and adipocytefunctions such as adiponectin and leptin. In adipocytes, PPARγ regulatesthe expression of genes involved in lipid synthesis, storage, andtransportation (Berger and Moller (2002) Annu Rev Med 53, 409-435).PPARγ is essential to activate the promoters of acyl-CoA oxidase and aP2and many other fat-cell specific genes (Kliewer et al. (1992) Nature355, 446-449; Tontonoz et al. (1994) Cell 79, 1147-1156).

Coactivators play critical roles in this nuclear receptor directedadipogenesis program. The importance of coactivators in metabolism andadipogenesis are well documented (Castillo et al. (1999) EMBO J 18,3676-3687; Puigserver et al. (1998) Cell 92, 829-839; Puigserver andSpiegelman (2003) Endocrine Rev 24, 78-90; Qi et al. (2003) J. Biol.Chem. 278, 25281-25284; Ge et al. (2002) Nature 417, 563-567; Andersenet al. (2005) J Med Genet 42, 402-407; Wang et al. (2006) CellMetabolism 3, 111-122). Most coactivators identified to date interactwith PPARγ through its C-terminal AF-2 domain or LBD domain, which isdependent on or enhanced by ligand binding, and mediated by thesignature cofactor motif, LXXLL, (McInerney et al. (1998) Genes Dev. 12,3357-3368). For example, coactivators SRC-1/NCoA-1, CBP/p300, pCAF, andTRAP220 interact with the LBD domain of PPARγ (Robyr et al. (2000)Molecular Endocrinology 14, 329-347; Castillo et al. (1999) EMBO J 18,3676-3687; Nolte et al. (1998) Nature 395, 137-143; Zhu et al. (2000) J.Biol. Chem. 275, 13510-13516). Other coactivators such as PGC-1αinteract with PPARγ through the PPARγ DNA-binding and hinge domains(Puigserver et al. (1998) Cell 92, 829-839). PGC-2 binds to the PPARγA/B domain, which is independent of ligand and LXXLL motif binding. ManyNR coactivators such as members of p160/SRC and PGC-1 family are highlyversatile. They are expressed in a variety of tissues and coactivate awide spectrum of NRs including PPARγ (McKenna & O'Malley (2002) Cell108, 465-474; Puigserver et al. (1998) Cell 92, 829-839; and Lin et al.(2005) Cell Metab 1, 361-370). For example, PGC-1α is also a coactivatorfor estrogen receptor (ER)α. Multiple sites in PGC-1α govern itsinteraction with ERα, but the presence of an LXXLL motif is required forPGC-1α's ligand-dependent binding to ERα (Tcherepanova et al. (2000) J.Biol. Chem. 275, 16302-16308). Therefore, whether a ligand is requiredfor the NR-coactivator interaction mainly depends upon whether LBDdomain of NR is involved in the interaction.

Modulation of nuclear receptors, their cofactors, and their pathwayswill offer new avenues for therapeutic strategies to combat obesity anddiseases associated with an overweight as well as underweightconditions. Therefore, the inventor has sought to address the issue ofadipogenesis, through the use of the novel nuclear receptor coactivatorand its ability to promote or inhibit transcription.

SUMMARY OF THE INVENTION

The present invention relates to novel polypeptides with act ascofactors for the nuclear transcription factor PPARγ. The inventor hasdesignated these polypeptides, Constitutive Coactivator of PPARgamma(CCPG). These polypeptides and fragments of these polypeptides act ascoactivators and corepressors of PPARγ and thereby modulate PPARγadipocyte specific gene expression.

The invention also relates to isolated nucleotide sequences, whichexpress CCPG polypeptides and CCPG fragments with PPARγ transcriptionalactivating or inhibiting activity.

The invention also relates to interference RNA capable of specificallyinhibiting translation of a CCPG polypeptide in a cell.

The invention also relates to nucleotide sequences encoding CCPGpolypeptides, further incorporated into expression vectors or nucleotidedelivery systems.

Therefore, the invention relates to a composition capable of effectingadipogenesis by modulating PPARγ activation and adipocyte specific geneexpression.

It is envisioned that the instant invention may be used in vitro for thestudy of adipogenesis, obesity or related conditions, and/or, may beadministered in vivo for the treatment of uncontrolled adipogenesis,obesity or related conditions.

REFERENCE TO COLOR FIGURES

The application file contains at least one figure executed in color.Copies of this patent application publication with color photographswill be provided by the Office upon request and payment of the necessaryfee.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the proposed mechanism of CCPG in adipocyte specificgene expression. (A) Corepressors bind to PPARγ and RXRα, preventingfurther interaction with coactivators and gene transcription. (B) CCPGbinds to PPARγ and RXRα, displacing corepressors and allows recruitmentof coregulators p62, p44, cdk7, XPD and possibly other coactivators.Adipocyte specific gene transcription and adipogenesis is theninitiated.

FIG. 2 illustrates the cloning and alignment of CCPG sequences. (A)Alignment of mouse (SEQ ID NO:1), human (SEQ ID NO:2), rat (SEQ IDNO:3), dog (SEQ ID NO:4), and bovine (SEQ ID NO:5) CCPG amino acidsequences. Shaded areas represent conserved amino acids among species.LXXLL motifs are underlined. (B) Schematic representation of thestructure of mouse CCPG. CCPG consists of an N-terminal XPG-like domain(XPD), a central viable hinge region (CVR) and a C-terminal conserveddomain (CCD). Putative and characteristic domains are marked withnumbers. (C) Western blot analysis of recombinant mouse CCPG withanti-CCPG polyclonal antibody. HEK-293 cells were transfected withplasmid pcDNA3-CCPG (lane 1) and pcDNA3 empty vector (lane 2) or withouttransfection (lane 3). The arrow indicates the recombinant CCPGexpressed as a ˜95 kD protein.

FIG. 3 illustrates the expression profile and subcellular localizationof CCPG. CCPG protein (A and C) and mRNA (B and D) expression in adultmouse tissues and embryos from embryonic day (E) 5 through E19 andpregnant mouse placenta and uterus (E13). CTL represents 293 cell lysateexpressing the recombinant mouse CCPG. Protein (100 μg) or 25 μg totalRNA isolated from various mouse tissues, embryos (E5 through E19),placenta and pregnant mouse uterus (E13) were used. Ethidium bromide(EtBr) staining of 18S/28S RNA was used as loading control. (E) CCPG islocalized in the nucleus. 3T3 cells were transfected with GFP-fusedfull-length CCPG. Cells were examined and photographed under afluorescence microscopy (400×) 24 hr after transfection. Scale barequals 10 μm.

FIG. 4 illustrates CCPG interaction with PPARγ and other nuclearreceptors in a ligand-independent manner. (A) For GST pull-down assays,COS7 cells were transfected with myc-tagged PPARγ, RXRα, ERα or TRβ. Thecell lysates were incubated with 20 μg of purified GST or GST-CCPGprotein immobilized on glutathione Sepharose beads in the presence (+)or absence (−) of ligand. For PPARγ Tro was used at 10 μM; for RXRα9-cis RA was used at 10 μM; for ERα, 17β-estrodiol was used at 1 μM; andfor TRβ, T3 was used at 1 μM; 10 percent of protein was used as inputloading for each pull-down, except that 5 percent was used for RXRα.HRP-conjugated anti-myc antibodies were used to detect the interactions.Please note that the input proteins are 1/10 for PPARγ, ERα and TRβ and1/15 for RXRα of the pulldown reactions. (B) For co-IP, HCT-116 cellswere co-transfected with Flag-tagged PPARγ plus GFP or GFP-CCPG andtreated with 1.0 μM Tro or 0.1 percent vehicle (DMSO). Cell lysates wereincubated with anti-GFP antibody, and PPARγ was detected by westernblotting with HRP-conjugated anti-Flag antibody. After stripping, themembrane was reprobed with anti-GFP or anti-GAPDH antibody,respectively.

FIG. 5 illustrates the Characterization of PPARγ-CCPG interaction. (A)Diagram of different PPARγ deletions according to a PPARγ structuremodule. (B) GST pull-down assays were performed using COS7-expressed,myc-tagged, different PPARγ deletions and purified GST or GST-CCPGimmobilized on glutathione Sepharose beads. The input lanes represent 10percent of the total volume of the lysate used for the pull-downs foreach sample. Interactions were detected by western blot with an anti-mycantibody. (C) Diagram of truncated N-terminal 1-561 and C-terminal562-786 CCPG tagged with GFP. (D). Co-IPs were performed exactly as inFIG. 4B. (E) Diagram of GFP-tagged CCPG mutants with a series of mutatedLXXLL motifs (LXXLL to LXXAA). (F) Co-IPs were performed exactly as inFIG. 4B.

FIG. 6 illustrates CCPG coactivativation of PPARγ and ERα, andN-terminus of CCPG possesses an activation domain. (A) HCT-116 cellswere cotransfected with 300 ng of PPRE-TK-LUC, 50 ng of PPARγ, 50 ng ofCCPG and 25 ng of a previously identified PPAR coactivator PGC-1αexpression plasmids with Tro (1.0 μM) or 0.1 percent vehicle (DMSO). (B)HCT-116 cells were cotransfected with 300 ng of PPRE-TK-LUC, 50 ng ofPPARγ, either 50 ng of CCPG, CCPG 1-561 or CCPG 562-786 expressionplasmids with Tro (1.0 μM) or 0.1 percent vehicle (DMSO). (C) HCT-116cells were cotransfected with 150 ng of PPRE-TK-LUC, 50 ng of PPARγ, 50ng of CCPG expression plasmids with increasing amount (5, 25, 100 ng) ofCCPG 1-561 or CCPG 562-786 expression plasmid plus Tro (1.0 μM) or 0.1percent vehicle (DMSO). Empty pCDNA3.1 plasmid was added to ensure equalDNA amount used in each transfection. (D) COS7 cells were cotransfectedwith the reporter plasmid pG5luc (Promega) containing five copies of theUAS linked to luciferase and plasmid expressing GAL4 DBD-fused CCPG orPGC-1α shown as a positive control. (E) HCT-116 cells were cotransfectedwith 300 ng of a native acyl-CoA oxidase (ACO) PPRE reporter plasmid, 50ng of PPARγ, and 50 ng of CCPG or empty vector plasmids supplementedwith Tro (1.0 μM). (F) MCF-7 cells were cotransfected with 300 ng of ERreporter pERE-TK-LUC and 25 ng of CCPG or empty vector plasmid in thepresence of 17β-estrodiol (100 nM) or vehicle (ethanol). All the fireflyluciferase and Renilla luciferase activities were determined 18-24 hrafter transfection. Data were normalized to Renilla luciferase activityderived from the internal control plasmid phR-TK. Values were expressedrelative to activation of empty vector and each value was derived fromat least three independent experiments. Statistical analysis was donevs. the value from PPARγ alone in the presence of Tro using Student'st-test. (*): p<0.05.

FIG. 7 illustrates the upregulation of CCPG expression and how CCPGinteracts with endogenous PPARγ in differentiating OP9 cells duringadipogenesis. (A) 10 μg of total RNAs were isolated on different datesfrom OP9 cells subjected to adipocyte differentiation-induced byadipogenic mix cocktail and hybridized with DIG-labeled CCPG probe.After stripping, membrane was rehybridized with DIG-labeled PPARγ 2probe. Ethidium bromide (EtBr) stained 28S RNA was used as loadingcontrol. (B) Western blot of CCPG and PPARγ during adipogenesis as in(A). (C) OP9 preadipocytes were subjected to an adipogenic mix cocktailstimulation, meanwhile infected with adenovirus expressing GFP orGFP-CCPG fusion proteins. On differentiation day 2, cells were lysisedfor Co-IP assay. Anti-GFP monoclonal antibody was used toco-immunopreciptiate GFP and GFP fusion protein, and anti-PPARγ antibodywas used to detect the interaction.

FIG. 8 illustrates CCPG promotion of adipogenesis of OP9 preadipocytes.(A) OP9 preadipocytes were transduced with an adenovirus expressingeither GFP (Ad-GFP) or CCPG fused to GFP (Ad-GFP-CCPG). The resultingcells were subjected to a standard differentiation for 4 days with 1/10concentration of the standard adipogenic mix cocktail in the media.Cells were fixed and stained with Oil-Red-O for microscopic examinationand photographed at 400× magnification. There are many positive cells(red) in OP9 cells treated with Ad-GFP-CCPG. (B Western blots forAdiponectin and perilipin protein in OP9 cells treated with eitherAd-GFP or AD-GFP-CCPG for 4 days. (C) In another set of experiments,total RNAs were extracted from the cells and subjected to real timeRT-PCR analysis. Adenoviral-CCPG RNAi was used to knockdown CCPGtranscripts and LacZ RNAi was used as control. (D) Oil Red O staining ofOP9 cells treated with only adipogenic mix cocktail (Control: CTL),Ad-LacZ RNAi or Ad-CCPG RNAi1, Ad-CCPG RNAi2 and Ad-CCPG RNAi2 mutation(RNAi2M) for 4 days. (E) Western blot analyses for CCPG, adiponectin,perilipin, and GAPDH in OP9 cells treated for 4 days. Scale bars: 30 μm.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to compositions and methods useful inregulating adipogenesis in cells. Specifically, the present inventionrelates to nucleotide sequences of mouse and (SEQ ID NO:6) human (SEQ IDNO:7), as well as rat (SEQ ID NO:8), canine (SEQ ID NO:9), and bovine(SEQ ID NO:10) which encode a CCPG. CCPG polypeptides which when presentin the nucleus of a cell, function as PPARγ coactivators. Also encodedby these nucleotide sequences are polypeptide fragments of CCPG, atleast one of which has been shown to coactivate PPARγ and at least oneof which has been shown to inhibit PPARγ activation. These nucleotidesequences, when expressed in a mammalian cell will enhance or inhibitPPARγ activity and the subsequently the transcription of adipogenicspecific genes. Disclosed are CCPG polypeptide fragments, and relatednucleotide sequences that activate or inhibit PPARγ. The presentinvention also relates to nucleotides sequences for interference RNA(RNAi), (SEQ ID NO:11, SEQ ID NO:12) which may be expressed in a cell toinhibit translation of endogenous CCPG, thereby reducing the amounts ofCCPG available to activate PPARγ, and reducing transcription ofadipogenic specific genes. The present invention also relates to methodsthat may be used to introduce a nucleotide sequences encoding a CCPG ora CCPG RNAi into mammalian cells.

PPARgamma

Peroxisome proliferators activated receptor gamma (PPARγ) is a principaltranscription factor in the determination of adipogenesis. It is knownto require interaction with several coregulators before it will initiatetranscription of adipogenic genes. Initiation of gene transcriptionrequires the binding of a ligand to PPARγ. Normal ligands for PPARγ arefree fatty acids (FFAs) and eicosanoids. PPARγ forms a heterodimer withRXRα and further binds to the specific peroxisome proliferator responseelements (PPREs) of DNA to initiate gene transcription. This eventrequires recruitment of several additional transcriptional coactivatorsincluding p62, p44, cdk7, XPD and possibly others (Rosen and Spiegelman(2001) J. Biol. Chem. 276, 37731-37734).

Constitutive Coactivator of PPARgamma (CCPG)

The present invention relates to a polypeptide coactivator, designatedConstitutive Coactivator of PPARgamma or CCPG. CCPG binds and activatesPPARγ independent of ligand binding. As illustrated in FIG. 1 and in theexamples below, CCPG regulates activation of PPARγ and subsequently thetranscription of genes leading to adipogenesis. While not agreeing to bebound by theory, CCPG binds to elements of the basal transcriptioncomplex, PPARγ and RXRα (FIG. 1A). This binding displaces corepressormolecules associated with PPARγ and RXRα, and allows the recruitment ofcoregulators p62, p44, cdk7, XPD and possibly other coregulators (FIG.1B).

The inventor has cloned a nucleotide sequence, which expresses a mouseCCPG. Through a Genbank search the inventor found this sequence to behomologous with a nucleotide sequence (DQ873694), which encodes anuncharacterized mouse KIAA1838-like protein (NM_(—)024203). Also throughGenbank the inventor identified a nucleotide sequence associated withhuman chromosome 6, (NW_(—)923184) for which no polypeptide was known.The inventor cloned this human nucleotide sequence (DQ873695) anddiscovered that it expresses a human CCPG polypeptide (ABH09086).Subsequently, through Genbank, using the mouse CCPG polypeptide sequenceas a reference, the inventor further identified previouslyuncharacterized polypeptides with close homology to mouse CCPG, whichthe inventor designated rat (XP_(—)218006), canine (XP_(—)855466), andbovine (XP_(—)602628) CCPG (Table 1).

Disclosed are polypeptide sequences of the Constitutive Coactivator ofPPARγ (CCPG) of mouse (SEQ ID NO:1), human (SEQ ID NO:2), rat (SEQ IDNO:3), canine (SEQ ID NO:4), and bovine (SEQ ID NO:5). These CCPGpolypeptides or fragments of these CCPG polypeptides will modulate theactivation of transcription factor PPARγ and subsequently transcriptionof adipogenic genes. Also disclosed are nucleotide sequences encodingmouse (SEQ ID NO:6), human (SEQ ID NO:7), rat (SEQ ID NO:8), canine (SEQID NO:9), and bovine (SEQ ID NO:10) CCPG polypeptides or fragments ofCCPG polypeptides.

Nucleotide sequences encoding CCPG polypeptides or fragments thereofwhen introduced into the nucleus of a mammalian cell, will express aCCPG which will modulate the activation of transcription factor PPARγand the subsequent transcription of adipogenic genes. Therefore, oneembodiment of the present invention is directed to isolated humannucleotide sequence encoding a CCPG polypeptide or fragment of a humanCCPG polypeptide with PPARγ activator or repressor activity. Anotherembodiment is directed to nucleotide sequences encoding fragments ofmouse CCPG polypeptides with PPARγ activator or repressor activity.These nucleotide sequences when expressed in a mammal cell provide CCPGpolypeptides, or fragments of CCPG polypeptides, which localize to thenucleolus and either, enhance or inhibit the adipogenic transcriptionalactivity of PPARγ.

As demonstrated in the examples, a nucleotide sequence of SEQ ID NO:6,when expressed in a cell, will provide expression of the full lengthCCPG polypeptide set forth in SEQ ID NO: 1. This polypeptide willfunction as a coactivator of PPARγ thereby initiating transcription ofadipogenic specific genes in mammalian cells.

Similarly, also demonstrated in the examples, an isolated nucleotidesequence encoding amino acid residues 1-561 of SEQ ID NO:1, whenexpressed in a cell, will provide a polypeptide fragment of CCPG. Thispolypeptide will also function as a coactivator of PPARγ and willinitiate transcription of adipogenic specific genes.

Alternatively, a nucleotide encoding amino acid residues 562-786 of SEQID NO:1, when expressed in a cell, will provide a polypeptide with PPARγcorepressor properties, thereby inhibiting PPARγ activation. CCPG hasmultiple sites of contact with PPARγ and therefore possibly multipleregions with activating or inhibitory activity. One of ordinary skill inthe art will appreciate that by encoding shorter polypeptide fragmentsof CCPG and expressing them in a cell, one would be likely to identifypolypeptides of fewer residues that possess the PPARγ activatingproperties of the CCPG coactivating polypeptide (1-561 SEQ ID NO:1), or,alternatively, the inhibitory properties of the CCPG corepressorpolypeptide (562-786 SEQ ID NO:1). One of ordinary skill in the art willalso appreciate that various mutations or derivations of thispolypeptide sequence, including amino acid substitutions, insertions, ormodifications, may also result in a CCPG polypeptide with increased ordecreased PPARγ activating capacity. The inventor has identified amethod of rapidly screening and identifying polypeptides or compoundswith for PPARγ regulatory activity (Example 7). The inventor alsoprovides an antibody that may be useful to identify or localize a CCPGpolypeptide, for example in western blots, or immunocyte chemistry(Example 1).

Then inventor has identified and cloned CCPG from mouse and human, andby sequence comparison in Genbank has identified homologs in rat,canine, and bovine. These amino acid sequences from mouse, human, rat,canine, and bovine share from 92 to 67 percent identity (Table 1).Regions of varying sequence identify are dispersed though out the CCPGpolypeptides of mouse, human, rat, dog, and cattle (FIG. 2A). It is wellknown that amino acid sequences, which are highly conserved betweenspecies, are also likely to be functional across different species,whereas non-conserved amino acid sequences may often be substitutedwithout a loss of activity. It is also known that polypeptide fragmentswith conserved amino acid sequences are likely to possess the variousfunctional activities of the intact polypeptide. The inventor hasdetermined amino acid sequence identity is more closely conserved inspecific regions of the CCPG polypeptide. For example, amino acidresidues 1-320 of mouse and human CCPG are conserved at 87 percentidentity (Table 2). Similarly, amino acid residues 420-786 of mouse andhuman CCPG are conserved at 80 percent identity. A CCPG polypeptide, orfragment thereof, which incorporates these or other conserved amino acidis likely to possess PPARγ activation or repression properties, and, isalso likely to exhibit these properties in mice, humans or othermammals. Therefore, another embodiment is an isolated nucleotidesequence which expresses a polypeptide with sequence identity to SEQ IDNO:1 or SEQ ID NO:2 or fragments thereof. By way of example, an isolatednucleotide sequence which encodes a polypeptide with 99 percent, 95percent, 90 percent, 85 percent, 80 percent, 75 percent, 70 percent, and68 percent identity with SEQ ID NO:1 or SEQ ID NO:2 or fragmentsthereof.

These CCPG polypeptides or fragments of CCPG polypeptides, encoded byisolated nucleotide sequences, maybe further incorporated intoexpression vectors, and/or delivery systems including viral deliverysystems and transfected into cells where they may be expressed so as toregulate PPARγ activation and subsequently adipogenesis. In addition,these nucleotide sequences, amino acid sequences, and antibodies areinvaluable tools in the study of adipogenesis.

RNA Interference (RNAi)

Another embodiment of the invention comprises an isolated nucleotidesequence capable of inhibiting CCPG translation generally known as anantisense nucleotide, small interference RNA, or RNA interference(RNAi). RNA interference or “RNAi” is a term initially coined by Fireand co-workers to describe the observation that double-stranded RNA(dsRNA) can block gene expression when it is introduced into worms (Fireet al. (1998) Nature 391, 806 811, incorporated herein by reference).dsRNA directs gene-specific, post-transcriptional silencing in manyorganisms, including vertebrates, and has provided a new tool forstudying gene function. RNAi involves mRNA degradation, but many of thebiochemical mechanisms underlying this interference are unknown. The useof RNAi has been further described in Carthew et al. (2001) CurrentOpinions in Cell Biology 13, 244 248, and Elbashir et al. (2001) Nature411, 494 498, both of which are incorporated herein by reference. Also,see, e.g., U.S. Pat. Nos. 7,022,828, 7,150,970, 7,101,991, and7,078,196, which are herein incorporate by reference. The RNAi moleculesof the present invention are double-stranded or single-stranded RNA offrom about 10 to about 100 nucleotides that inhibit RNA translation.That is, the isolated RNAi of the present invention mediate degradationof mRNA of the CCPG gene, thereby preventing its translation andreducing CCPG available for activation of PPARγ, and subsequentlyadipogenic gene transcription. By way of example but not of limitation,an RNAi containing the appropriate homology is set forth in sequencesSEQ ID NO:11 and SEQ ID NO:12.

CCPG Vectors and Viral Delivery Systems

The nucleotide sequences may be used per se or further inserted into asuitable expression vector such as a plasmid or viral vector construct.Therefore, another embodiment is an expression vector capable ofexpressing a nucleotide sequence encoding the CCPG polypeptide such thatwhen the CCPG polypeptide is expressed it may interact with nuclearreceptors including PPARγ. Yet another embodiment is an expressionvector encoding a RNAi capable of inhibiting CCPG expression. A verityof expression or transfection vectors are known in the art and arecommercially available as are methods to insert these nucleotidesequences encoding polypeptides or RNAi of interest. Once the codingsequence of one or more CCPG polypeptides has been obtained, it may beoperably linked to suitable control elements to provide an expressiblenucleotide sequence using standard cloning or molecular biologytechniques. See, e.g., Edge (1981) Nature 292:756; Nambair et al. (1984)Science 223:1299; and Jay et al. (1984) J. Biol. Chem. 259:6311.Expression vectors that may be effective for the expression of CCPGpolypeptides that activate PPARγ include, but are not limited to, thePCDNA 3.1, EPITAG, PRCCMV2, PREP, PVAX, PCR2-TOPOTA vectors (Invitrogen,Carlsbad Calif.), PCMV-SCRIPT, PCMV-TAG, PEGSHIPERV (Stratagene, LaJolla Calif.), and PTET-OFF, PTET-ON, PTRE2, PTRE2-LUC, PTK-HYG(Clontech, Palo Alto Calif.). CCPG polypeptides may be expressed using(i) a constitutively active promoter, (e.g., from cytomegalovirus (CMV),Rous sarcoma virus (RSV), SV40 virus, thymidine kinase (TK), orP.beta.actin genes), (ii) an inducible promoter (e.g., thetetracycline-regulated promoter (Gossen, M. and H. Bujard (1992) Proc.Natl. Acad. Sci. USA 89:5547-5551; Gossen, M. et al. (1995) Science268:1766-1769; Rossi, F. M. V. and H. M. Blau (1998) Curr. Opin.Biotechnol. 9:451-456), commercially available in the T-REX plasmid(Invitrogen)); the ecdysone-inducible promoter (available in theplasmids PVGRXR and PIND; Invitrogen); the FK506/rapanmycin induciblepromoter; or the RU486/mifepristone inducible promoter (Rossi, F. M. V.and Blau, H. M. supra)), or (iii) a tissue-specific promoter or thenative promoter of the endogenous gene encoding leptin from a normalindividual.

Once constructed, the nucleotide sequences including those thatincorporate RNAi may be administered using standard gene deliveryprotocols. Methods for gene delivery are known in the art, including butnot limited to methods based on naked nucleic acids, liposomes, cells,retrovirus including lentiviruses, adenovirus and parvoviruses includingadeno-associated virus herpes simplex virus. See, e.g., U.S. Pat. Nos.5,589,466, 6,936,272, 5,399,346, 6,818,209, 7,232,899, and 6,106,826which are hereby incorporated by reference. Other gene deliverymechanisms include liposome-derived systems, artificial viral envelopes,and other systems known in the art (See, e.g., Rossi, J. J. (1995) Br.Med. Bull. 51(1):217-225; Boado, R. J. et al. (1998) J. Pharm. Sci.87(11):1308-1315; and Morris, M. C. et al. (1997) Nucleic Acids Res.25(14):2730-2736; El-Aneed, (2004) J Control Release 94, 1-14 all,herein incorporated by reference). Lentiviruses have been used for smallinterfering RNA and described (Li and Rossi (2005) Methods Enzymol 392,226) and hereby incorporated by reference.

Administration of Nucleotides Encoding CCPG or RNAi

The various embodiment described herein are water-soluble and may beadministered, by way of example, in a sterile aqueous solution,preferably a physiological solution. A pharmaceutically acceptableformulation of the present invention may be any injectable or topicallyapplied physiological solution. A physiological solution may becomprised of isotonic balanced salts with a pH of about 7.0 to about7.5. A preferred physiological solution may comprise isotonic saline anda pH of 7.5. For a topical administration or for certain targetedapplications it may be desirable to increase the viscosity of theformulation. Various carries known to increase viscosity include but arenot limited to such high molecular weight polymers such as, hyaluronicacid, hydroxypropyl methyl cellulose, as well as other carbohydrates orsugars. These are typical included in the formulation at 0.01 to 0.1percent, 0.1 to 1.0 percent, 1 to 2 percent, 2 to 3 percent, 3 to 4percent, 4 to 5 percent 5 to 10 percent, or 10 to 20 percent by weight.By way of example and not of limitation, recombinant viruses may beadministered at a dose of 10⁷-10¹² pfu for a non-intravenousadministration.

A wide variety of administration routes may be employed. The route, bywhich the nucleotide sequence or virus is administered, as well as theformulation, carrier, or vehicle, will depend on the target site as wellas the desired effect. For example, if systemic administration isdesired any intravenously or intravascularly injection may be employed.A single-time (bolus) injection is a possibility, as is continuousinfusion. Alternatively, if a targeted administration is desired, asubcutaneous injection, or application to exposed tissues during courseof surgery may also be employed. It may be desirable to administer CCPGencoding nucleotides as an adjunct to surgical procedure. By way ofexample, CCPG encoding nucleotides may be applied directly to tissueexposed during surgery. Promoting the genesis adipose tissue may bedesirable for filling or augmenting soft tissue during cosmetic orreconstructive surgery. Various methods of administrating nucleotidesequence in vivo including vectors and delivery systems are furtherdescribed by Mah et al., including organ targeted delivery,microencapsulation of recombinant cells, ex vivo transduction of stemcells, systemic delivery and vector targeting, (for review see Mah etal., (2002) Clin Pharmacokinet 41, 901-911 herein incorporated byreference). By way of example, for targeted soft tissue injections,recombinant viruses can be diluted in Dextrose-5 percent in a totalvolume that is 5-30 percent of the total estimated volume of a lesion tobe injected. The recombinant virus can be administered by multipleinjections at approximately 1 cm increments, three-dimensionally tocover the entire lesion. Virus may be administered multiple timesdepending on safety and efficacy.

The foregoing disclosure of methods for the administration of nucleotidesequences encoding CCPG polypeptides, applies equally to nucleotidesequence encoding RNAi for regulation of adipogenesis.

Applications

The CCPG nucleic acids and proteins of the invention are useful inpotential diagnostic and therapeutic applications and as research tools.These include serving as a specific or selective nucleic acid or proteindiagnostic and/or prognostic marker, wherein the presence or amount ofthe nucleic acid or the protein are to be assessed. These also includepotential therapeutic applications such as the following: (i) a proteintherapeutic; (ii) a small molecule drug target; (iii) an antibody target(therapeutic, diagnostic, drug targeting/cytotoxic antibody); (iv) asdescribed above, a nucleic acid useful in gene therapy (genedelivery/gene ablation); and (v) and an agent promoting tissueregeneration in vitro and in vivo.

There is a multitude of conditions in which it may be desirable tomodulate the generation of adipose tissue. Conditions in which it wouldbe desirable to promote generation of adipose tissue include but are notlimited to, subjects suffering from wasting diseases, subjectschronically underweight, livestock underweight, subjects undergoingcosmetic or reconstructive surgery, or, treatment in place of cosmeticor reconstructive surgery. Conditions in which it would be desirable toinhibit the generation of adipose tissue include but are not limited to,subject chronically overweight, subjects suffering from obesity,subjects undergoing cosmetic or reconstructive surgery or, treatment inplace of cosmetic or reconstructive surgery. Also included are in vitroapplications. Any application where cell differentiation is critical tosuccess in the development of therapeutic strategies. By way of examplestem cells, mesenchyme cells, and preadipose cells, which may be used intransplantation, ex vivo tissue reconstruction or tissue engineering(see Patrick et al., (2001) The Anatomical Record, 263:361-366). It maybe desirable to prevent, enhance, or inhibit adipogenesis in thesecells. By way of example, it may be desirable to repress adipogeneticgene expression in cells used for reconstruction of bone or cartilagetissue. Alternatively, it may be desirable to induce adipogenic tissuefor cosmetic or reconstitute surgery by way of example for filling asoft tissue defect.

DEFINITIONS

The term “CCPG” or “PGCC” refers to a Constitutive Coactivator ofPPARgamma of the instance invention, a polypeptide with properties thatinclude that of a coactivator or the regulation or modulation of nucleartranscription factor PPARγ.

The term “CCPG polypeptide” refers to a CCPG from any source or afragment of a CCPG from any source with PPARγ transcriptional regulatingor modulating activity.

The term “adipogenesis modulating factor” means any agent that enhancesor inhibits the interactions of transcriptional factors capable orpromoting adipogenesis.

The term “adipogenesis” and “influencing adipogenesis,” regulatingadipogenesis, or modulating adipogenesis as used herein refers to anyincrease or decrease of adipogenic gene expression or expression ofadipocyte-specific markers, including but not limited to the expressionof adiponectin and perilipin polypeptides or their related nucleotidesequences. Also included is any increase in the accumulation of fats oroils within cell compartments or the differentiation of a cell to anadipocyte by any detectable means including morphological.

The term “coactivator” or “coactivating” as used herein refers to anycomposition including a protein, polypeptide, amino acid sequence,nucleotide sequence, or fragment thereof or small molecule mimic thereofwhich activates PPARγ and enhances or increases PPARγ transcriptionpromoting activity.

The term “corepresor” or “corepressing” as used herein refers to anycomposition including a protein, polypeptide, amino acid sequence,nucleotide sequence, or fragment thereof or small molecule mimic thereofwhich represses PPARγ activation and inhibits or decreases PPARtranscription activity.

The acronym “CREB” as used herein refers to cAMP-responseelement-binding protein.

The term “reporter” as used herein refers to chemical or enzymaticmarkers that may be attached to a nucleotide or amino acid sequence,allowing the identification and/or localization of theses molecules. Byway of example, fluorescent reporters such as fluorescence or rhodamine,enzyme reporters such as horseradish peroxidase, alkaline phosphatase,or radioactive isotopes, may be attached to a nucleotide or amino acidsequence.

The term “PPARγ reporter” as used herein refers to a nucleotide sequenceoperably linked to a reporter such that initiation of transcription ofthe nucleotide sequence by PPARγ results in expression or activation ofthe reporter including but not limited to the PPARγ-responsiveluciferase reporter construct PPRE-TK-LUC.

The acronym “NR” as used herein refers to Nuclear receptor.

The acronym “PGC-1” as used herein refers to PPARγ coactivator-1.

The acronym “CCPG” as used herein refers to PPAR gamma constitutivecoactivator-1.

The acronym “PPAR” as used herein refers to peroxisome proliferatorsactivated receptor.

The acronym “PPRE” as used herein refers to peroxisome proliferatorresponse elements.

The acronym “RXR” as used herein refers to retinoid X receptor.

The acronym “SRC” as used herein refers to steroid receptor coactivator.

The acronym “TFIIH” as used herein refers to transcription initiationfactor 11H.

The acronym “TRAP” as used herein refers to thyroid hormonereceptor-associated protein

The acronym “Tro” as used herein refers to troglitazone.

The acronym “XPG-like” as used herein refers to xeroderma pigmentosumgroup G-like.

The term “vector” or “expression vector” as used herein refers to apolynucleotide that enables the expression of a constituentpolynucleotide in a cell, wherein expression means the transcription ofDNA into RNA. Vectors include any oan all plasmids of viral vectorsincluding retroviral vectors, such as pLin for the expression ofantisense polynucleotides, and vectors that enable the continuous orstable expression of siRNAs, such as pSUPER.

The term “transfection” refers to the introduction of a vector in to acell whereby the vector is expressed. By way fo example these methodsinclude naked nucleotides per se, viral deliver systems, liposomes, useof Ca²⁺ in culture media, cell fusion. Transfection may take place invivo including introducing the vector to an human or animal, or ma takeplace in vitro, including cell culture conditions.

The term “cell” as used herein refers to a eukaryotic cell, preferable amammilla cell. Cells may exist in vitro including in a animal, or invivo including in cell culture.

A “conservative amino acid substitution” is one in which an amino acidresidue is replaced with another residue having a chemically similarside chain. Families of amino acid residues having similar side chainshave been defined in the art. These families include amino acids withbasic side chains (e.g., lysine, arginine, histidine), acidic sidechains (e.g., aspartic acid, glutamic acid), uncharged polar side chains(e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine,cysteine), nonpolar side chains (e.g., alanine, valine, leucine,isoleucine, proline, phenylalanine, methionine, tryptophan),beta-branched side chains (e.g., threonine, valine, isoleucine) andaromatic side chains (e.g., tyrosine, phenylalanine, tryptophan,histidine).

As used herein, “percent Identity” or of two amino acid sequences or oftwo nucleic acids is determined using the algorithm of Karlin andAltschul (Proc. Natl. Acad. Sci. USA 87:2264-2268, 1990), modified as inKarlin and Altschul (Proc. Natl. Acad. Sci. USA 90:5873-5877, 1993).Such an algorithm is incorporated into the NBLAST and XBLAST programs ofAltschul et al. (J. Mol. Biol. 215:403-410, 1990). BLAST nucleotidesearches are performed with the NBLAST program, score=100,wordlength=12, to obtain nucleotide sequences homologous to a nucleicacid molecule of the invention. BLAST protein searches are performedwith the XBLAST program, score=50, wordlength=3, to obtain amino acidsequences homologous to a reference polypeptide. To obtain gappedalignments for comparison purposes, Gapped BLAST is utilized asdescribed in Altschul et al. (Nucleic Acids Res. 25:3389-3402, 1997).When utilizing BLAST and Gapped BLAST programs, the default parametersof the respective programs (e.g. XBLAST and NBLAST) are used. Seehttp://www.ncbi.nlm.nih.gov.

Table 1 shows the calculations of identity for comparisons of CCPGpolypeptides from various mammalian species relative to mouse CCPG.TABLE 1 Percent Identity of CCPG Amino Acid Sequences Species(Nucleotide Amino Acid Accession Accession Number) Number PercentIdentity Mouse (DQ873694) ABH09085 100 Human (DQ873695) ABH09086 67 Rat(XM_218006) XP_218006 92 Canine (XM_855466) XP_855466 79 Bovine(XM_602628) XP_602628 67

TABLE 2 Species (Amino Acid Amino Acid Accession Residues) NumberPercent Identity Mouse (1-320) ABH09085 100 Human (1-320) ABH09086 87Mouse (420-786) ABH09085 100 Human (420-786) ABH09086 80

Preferred embodiments of the invention are described in the followingexamples. Other embodiments within the scope of the claims herein willbe apparent to one skilled in the art from consideration of thespecification or practice of the invention as disclosed herein. It isintended that the specification, together with the examples, beconsidered exemplary only, with other embodiments possible within thescope and spirit of this disclosure.

EXAMPLES

As illustrated in the examples below, the inventor has identified andcharacterized a novel PPARγ coactivator CCPG, and explored its role inpromoting PPARγ-directed adipogenesis. The ability of CCPG in PPARγtransactivation is similar to PGC-1α. However, it was determined thatinteractions between CCPG and PPARγ were independent of PPARγ ligandbinding. CCPG may enhance PPARγ function by synergizingligand-stimulated PPARγ transactivation, even though the CCPG-PPARγinteraction is not influenced by ligand or by recruiting othertranscription related proteins that promote PPARγ activity.

It was determined that CCPG has multiple sites in contact with PPARγ.Mutation of all 4 LXXLL motifs of CCPG did not compromise itsinteraction with PPARγ, implying novel structural characteristicspresent in CCPG. Though CCPG is ubiquitously expressed and interactswith PPARγ D hinge region, and PGC-1α interacts with part of PPARγ DNAbinding and D hinge region (36), a direct interaction between CCPG andPGC-1α by Co-IP was not observed (data not show). Nonetheless, asynergistic effect was seen in the in vitro PPRE luciferase reporterassay when CCPG and PGC-1α were co-expressed. This effect can bereconciled since both CCPG and PGC-1α are coactivators for PPARγ. Thesequential assembling of transcription machinery is a complex processinvolving participation of many transcription factors, coactivators, andcorepressors which play different roles. The different expressionprofiles of CCPG and PGC-1α also reflect their distinct roles inadipogenesis. The inventor further found that CCPG interacts with RXRαand ERα, but not with TRβ, suggesting CCPG may act as a selectivecoactivator for certain NRs.

A structure prediction reveals a Xeroderma pigmentosum G-like (XPG like)domain containing a helix-hairpin-helix (HhH)2 motif located in CCPGN-terminus. This characteristic domain is observed in DNA repair enzymesand in DNA polymerases (Sancar et al. (2004) Annual Review ofBiochemistry 73, 39-85). The HhH2 motif is capable of binding tosingle-stranded DNA (Tsodikov et al. (2005) Proceedings of the NationalAcademy of Sciences 102, 11236-11241) and plays a role in segregatingachiasmate chromosomes during meiosis (Cui and Hawley (2005) Genetics171, 1823-1835), probably facilitating to form an openingtranscriptional complex in the promoter region. The highest expressionlevels of CCPG in testis may be related to this process. The inventorspeculated that upon unwinding double stranded DNA in the promoterregion, CCPG may bind to single-stranded DNA with its HhH2 motif andinteracts with the hinge region of PPARγ to accelerate transcription.However, more detailed studies are warranted to answer whether CCPGbears nuclease activity and plays a role in DNA repair and replication.

CCPG truncation studies have shown that the N-terminus of CCPG (1-561)possesses an activating function for PPARγ, and its C-terminus acts asan inhibitor of PPARγ activation. These opposing functions may work toprecisely regulate PPARγ activate. The modulation of CCPG on PPARγtransactivation and adipogenesis was explored in cell culture. It wasdemonstrated that CCPG promotes adipogenesis of OP9 preadipocytes whenCCPG was introduced in to cells. Furthermore it was determined that wheninterfering RNA was used to disrupt translation of CCPG, adipogenesiswas inhibited.

The following examples support that CCPG may enhance PPARγ function bysynergizing ligand-stimulated PPARγ transactivation even though theCCPG-PPARγ interaction is not influenced by ligand binding or byrecruiting other transcription related proteins that promote PPARγactivity.

In summary, the inventor discloses that CCPG, which not only interactswith PPARγ but also with RXRα and ERα, is a bona fide coactivator forPPARγ that promotes adipogenesis. CCPG may be manipulated to regulatePPARγ transactivation and adipogenesis as demonstrated by transfectionof a preadipocyte nucleotide encoding a CCPG or an RNAi targeting CCPGtranslation. Moreover, CCPG promoted adipogenesis may have certain rolesin obesity and disruption of CCPG-PPARγ interaction may provide a newmethod for the prevention and therapy of obesity and related disorders.

Materials and Methods

Elements of the inventor's methodology not described herein aregenerally well known and detailed in numerous laboratory protocols,including Molecular Cloning 2nd edition, (1989) Sambrook, J., Fritsch,E. F., and Maniatis, J., Cold Spring Harbor., and Current Protocols inMolecular Biology, volumes 1-3, John Wiley and Sons, Inc. hereinincorporated by reference.

Cells, Plasmid, Antibodies, and Animals. HCT-116, COS7, and NIH3T3 cellswere cultured in medium recommended by American Type Culture Collection(ATCC, Manassas, Va.). On the day of transfection, the medium wasswitched to medium containing 10 percent charcoal/dextran-treated FBS(Hyclone, Logan, Utah). PPAR reporter plasmid PPRE-TK-LUC, RXRα andPPARγ expression constructs were described previously (Zhu et al. (1996)Gene Expr 6, 185-195; Zhu et al. (1997) J Biol Chem 272, 25500-25506)and were used as PCR templates. PGC-1α expression plasmid was fromAddgene (Cambridge, Mass.) (Puigserver et al. (1998) Cell 92, 829-839).The CCPG mutant (LXXLL to LXXAA) expression constructs were generatedusing GeneTailor site-directed mutagenesis kit (Invitrogen). All otherexpression constructs were generated by PCR cloning and validated by DNAsequencing. A rabbit anti-CCPG antibody was generated using synthesizedpeptide GILGEDTDYLIYDTC (SEQ ID NO:13) as antigen (Lampire BiologicalLaboratories, PA). Adiponectin and perilipin antibodies were from Sigma(St. Louis, Mo.). All other antibodies were purchased from Santa CruzBiotechnology (Santa Cruz, Calif.). All protocols and procedures wereapproved by the Animal Care and Use Committee of Saint Louis Universityand followed the NIH Guide for the Care and Use of Laboratory Animals.Mouse tissues were removed and collected from male (8 weeks old) orfemale pregnant C57BL/6 mice (Jackson Laboratories) at the specifiedtime points after halothane overdose inhalation.

Northern and Western Blot Analyses. Total RNA (25 μg) isolated frommouse tissues or embryos were separated on 1 percent formaldehydeagarose gels and transferred to nitrocellulose membranes. The 1.5 kbDIG-labeled CCPG cDNA probe was hybridized with the membranes overnight.The membrane was visualized using an HRP-conjugated anti-DIG antibody(Roche, Indianapolis, Ind.). Western blots were performed according tothe methods reported previously (Tong et al. (2006) Am. J. Respir. CellMol. Biol. 34, 28-38).

Transient Transfection and Reporter Assay. HCT-116 cells wereco-transfected with plasmids as indicated. After 5 hour incubation,cells were treated with appropriate medium supplemented with 10 percentcharcoal/dextran-treated FBS (Hyclone) and 1.0 μM Tro or 0.1 percentvehicle (DMSO). The luciferase activity was measured 16-20 h aftertransfection and the transfection efficiency was normalized by dividingthe firefly luciferase activity by the Renilla luciferase activityaccording to the Dual-Luciferase Reporter Assay kit manual (Promega,Madison, Wis.).

Real-time RT-PCR. Total RNAs were isolated using Trizol reagent(Invitrogen) and reverse-transcribed into First-Stranded cDNAs (Roche).Real-time RT-PCR of CCPG expression was performed using the SYBR GreenPCR Master Mix and ABI Prism 7700 Sequence Detector (Applied Biosystems)with forward primer 5′-GAA GCA CTC ATG TGT ACA CAC CCTG-3′ (SEQ IDNO:14) and reverse primer 5′-CCA CTC CTT GAC CAC TGG GCC AG-3′. (SEQ IDNO:15) The value of each sample was normalized to that of GAPDH.

Adenovirus Preparation. cDNA encoding GFP or GFP-CCPG was inserted intothe pAd/CMV-V5-DEST Gateway adenoviral vector and the adenoviruses ofAd-GFP and Ad-CCPG were prepared and titrated in 293A cells according tothe manufacturer's instructions (Invitrogen, Grand Island, N.Y.). Theadenovirus-delivered small hairpin RNA interference (shRNAi) was used toknockdown target gene expression. Briefly, oligonucleotides representingCCPG or LacZ used as negative control (provided by Invirogen) wereannealed, cloned into pENTR/H1/TO vector (Invitrogen), then subclonedinto adenoviral vector pAd/BLOCK-iT-DEST (Invitrogen) according to themanufacturer's instructions. The sense strands of the CCPG RNAi and itsmutant sequence were as follows (including linkers): CCPG RNAi1 5′-CACCGC AAA TGG TGA GTT TAA ATC CCG AAG GAT TTA AAC TCA CCA TTT GC-3, (SEQID NO:11) and CCPG RNAi2 5′-CAC CGC CCA CAC ATA TGT ACC ATA GCG AAC TATGGT ACA TAT GTG TGG GC-3′ (SEQ ID NO:12). For the CCPG RNAi control, themutated sequence from CCPG RNAi2 was 5′-CAC CGC TTA GAG ATA ACA ACC ATAGCG AAC TAT GGT TGT TAT CTC TAA GC-3′(SEQ ID NO:16), which has beenshown no significant similarity found in BLAST search.

Example 1 Cloning, Expression, and Subcellular Localization of CCPG

CCPG was identified, cloned, characterized, and localized at thesubcellular level as follows. The inventor performed a cDNA microarray(Incyte Genomics, 9400 gene elements) on hypoxia-treated mouse lungs (10percent O² for 4 days) and found that Expressed Sequence Tag (EST)W62706 was increased 2.7-fold among 270 unregulated genes (data notshown) (Teng et al. (2003) Circ Res 92, 1065-1067). The nucleotidesequence of EST W62706 was used to search the GenBank database and wasfound to be homologous to the transcript (accession number:NM_(—)024203) encoding an uncharacterized KIAA1838-like protein. Basedon the sequence information, the inventor then cloned the full-lengthcDNA sequence using Rapid Amplification of cDNA Ends (RACE) (GenBankaccession number: DQ873694). For 5′-RACE, first-strand cDNA wassynthesized by using CCPG gene-specific primer 5′-GAG ACA GCA CAT GGCGTC CAC CAC G-3′ (SEQ ID NO:17) and adult mouse lung total RNA astemplate. An oligo-dT anchor primer 5′-GAC CAC GCG TAT CGA TGT CGA CTTTTT TTT TTT TTT TT(A/C/G)-3′ (SEQ ID NO:18), and a nested CCPG genespecific primer 5′-GGT GAC GCT CTG CCA GCT CGT GG-3′ (SEQ ID NO:19),were used to amplify the 5′-end of CCPG cDNA. For 3′-RACE, first-strandcDNA was synthesized by using above oligo-dT anchor primer. The 3′-endof CCPG cDNA was amplified by using the primer 5′-GAC CAC GCG TAT CGATGT C-3′ (SEQ ID NO:20), and the CCPG specific primer 5′-CGT AGG CAG AACGCA TTG GGA CTC-3′. (SEQ ID NO:21),

To investigate the function of the protein encoded by this novel cDNA,the inventor performed yeast 2-hybrid screening for its potentialinteraction partner(s). The yeast two-hybrid screen was performedfollowing the Matchmaker GAL4 Two-Hybrid System 3 kit (Clontech)protocol. The CCPG cDNA was inserted into the GAL4 DNA-binding domain ofpGBKT7 bait plasmid (pGBKT7-CCPG) and used to screen a mouse 17-dayembryo cDNA library constructed in the pACT2 plasmid expressing the GAL4activation domain. pGBKT7-CCPG was transformed into yeast AH109 andmaintained in tryptophan-Dropout medium (AH109-CCPG). The mouse 17-dayembryo cDNA library was transformed into yeast AH109-CCPG, and positivecolonies appeared in blue on X-α-Gal containing medium due to secretionof α-galactosidase.

Using this cDNA as bait, the 17-day mouse embryo cDNA (1.4×10⁶ clones)library was screened and yielded 13 strong positive colonies under highstringency selection strategy. One of the positive clones encoded thenuclear receptor PPARγ. Further study demonstrated that this protein isconstitutively expressed in multiple adult mouse tissues and throughoutembryonic development. It enhanced PPARγ activity and was thereafterdesignated Constitutive Coactivator of PPAR gamma, or CCPG. Efforts havefocused on the investigation of the roles that CCPG plays in theinteraction, regulation of PPARγ transactivation, and adipogenesis.Northern blots showed that the transcript of mouse CCPG was ˜3.0 kb longencoding a protein of 786 amino acid residues with 4 characteristicLXXLL (L for Leucine and X for any amino acid) motifs.

The inventor has identified its human (GenBank accession number:DQ873695), mouse (DQ873694), rat (XM_(—)218006), dog (XP_(—)855466), andcattle (XP_(—)602628) homolog either with cDNA cloning (for mouse andhuman) or by searching current available databases, and found they werehighly conserved (FIG. 2A). A search for the human homolog revealed ahuman nucleotide sequence NW_(—)923184 associated with chromosome 6, forwhich no polypeptide was known. Using methodology described above formouse, the inventor cloned a novel human nucleotide sequence (SEQ IDNO:7) which expresses a novel human CCPG polypeptide (SEQ ID NO:2). Ananalysis of protein sequence alignment indicates that CCPG is composedof an N-terminal conserved XPG-like (xeroderma pigmentosum group G-like)domain (XLD) containing one LXXLL motif, a central variable hinge region(CVR), and a C-terminal conserved domain (CCD) containing 3 LXXLL motifs(FIG. 2B). A rabbit polyclonal antibody against mouse CCPG was raisedusing a synthetic peptide (GILGEDTDYLIYDTC) as antigen and mouse CCPGwas found to be expressed as a ˜95 KD molecular weight protein in HEK293 cells (FIG. 2C). Gene structure analysis indicates that CCPG frommouse and human consists of 11 exons and 10 introns, and is localized atchromosome 17(A1) in mice and 6q26-27 in humans. Northern and westernblots showed that CCPG was expressed in all adult mouse tissues examinedwith the higher expression in testis, brain, spleen, heart, and fattissues (FIGS. 3A and 3B). A time-course examination also showed thatCCPG was expressed throughout the embryonic developmental stages fromembryonic day 5 (E5) through E19, as well as in placenta and uterus ofpregnant mouse (E13) (FIGS. 3C and 3D). To determine its subcellularlocalization, CCPG was fused in-frame with GFP (GFP-CCPG), and whenexpressed in NIH3T3 cells, it localized entirely to the nucleus of thecells (FIG. 3E).

Example 2 Characterization of CCPG-PPARγ and Other NR Interactions

GST pull-down assays were performed to investigate CCPG interactions,and showed that CCPG interacts with PPARγ, RXRα, and ERα but not TRβ.GST or GST-CCPG fusion protein (subcloned into the pGEX-4T-2 vector) wasexpressed in E. coli. BL21 and purified by glutathione Sepharose 4Baffinity chromatography (Amersham, Piscataway, N.J.). COS7 cells weretransfected with appropriately tagged expression constructs or controlplasmid DNA. Cell lysates were incubated in binding buffer (50 mM HEPESpH 7.5, 120 mM NaCl, 1 mM EDTA, 1 mM DTT, 0.5 percent NP-40, 10 percentglycerol) plus a protein inhibitor cocktail (Roche) with ˜20 μg ofpurified GST or GST-CCPG fusion protein immobilized onglutathione-conjugated Sepharose 4B beads in the presence of ligand orvehicle (10 μM Tro and 10 μM 9-cis retinoid acid) for at least 3 hr, andwashed with binding buffer 4 times. Beads were boiled in protein1×SDS-PAGE loading buffer and the supernatants were analyzed by westernblot.

To determine whether CCPG interacts with NRs, Myc-tagged PPARγ, RXRα,ERα, and TRβ were expressed in COS7 cells and the resulting cell lysateswere incubated with purified GST or CCPG-GST fusion protein immobilizedon glutathione Sepharose 4B beads in the presence of ligand or vehicleas stated in figure legend. As shown in FIG. 4A, CCPG bound to PPARγRXRα and ERα, but not TRβ in a ligand-independent manner.

Example 3 CCPG Binds to PPARγ in a Ligand-Independent Manner

To further determine whether CCPG interacts with PPARγ in vivo, COS7cells were co-transfected with Flag-tagged PPARγ with either GFP orGFP-tagged CCPG expression vector, and then co-immunoprecipitated(Co-IP) with anti-GFP antibody. COS7 cells were cotransfected withplasmid vectors expressing Flag-tagged PPARγ plus plasmid vectorexpressing GFP or various GFP-tagged proteins. For those ligandtreatment assays, 16 hr after transfection, cells were treated with 1.0μM Tro or vehicle (0.1 percent DMSO) for additional 2 hr beforeharvesting. Cells were then washed with phosphate-buffered saline twiceand suspended in ice-cold IP binding buffer. For each IP assay, anti-GFPantibody was used to co-IP GFP or GFP fusion proteins in the presence orabsence of NR ligands (10 μM Tro for PPARγ or 10 μM 9-cis retinoid acidfor RXR) for 1 hr and then incubated with 50 μl of Protein A/G Plusagarose beads (Santa Cruz) for 3 hr at 4° C. Beads were washed withwashing buffer 4 times at 4° C. Co-precipitated proteins were releasedby boiling the beads in 1×SDS-PAGE loading buffer and analyzed bywestern blot. Western blots showed that CCPG interacted with PPARγ in aligand-independent manner (FIG. 4B). It was determined that CCPGinteracts with PPARγ in vivo in a ligand-independent manner.

Example 4 CCPG Binds to the D Hinge Region of PPARγ

To map the domain in PPARγ that mediates CCPG-PPARγ interaction, theinventor generated C-terminal myc-tagged PPARγ truncated expressionconstructs with corresponding domain deletions based on a PPARγstructure module (FIG. 5A) (Rosen and Spiegelman (2001) J. Biol. Chem.276, 37731-37734). Purified GST or GST-CCPG were incubated withCOS7-expressed, myc-tagged PPARγ truncated protein. Co-IP with ananti-myc antibody was used to detect the interactions between CCPG andPPARγ truncates. As shown in FIG. 5B, full-length PPARγ and PPARγ withdeletions of amino acids 1-205 still retained the binding ability toCCPG, but the more proximal PPARγ AF1 domain (amino acids 1-138) orPPARγ with deletion of amino acids 1-281 had shown no ability to bindCCPG, indicating that the D hinge region of PPARγ spanning amino acid205 to 280 is responsible for its interaction with CCPG.

Example 5 CCPG Utilizes its Multiple Sites to Interact with PPARγ

To determine the regions in CCPG that mediate its interaction withPPARγ, the inventor truncated CCPG in two large fragments: GFP-taggedCCPG N-terminus (1-561) and GFP-tagged C-terminus (562-786),respectively (FIG. 5C). Flag-tagged PPARγ was co-expressed either withGFP, or GFP-tagged CCPG fragments in COS7 cells. FIG. 5D showed thataddition of GFP antibody resulted in Co-IP of Flag-PPARγ with bothGFP-1-561 and GFP-562-786 of CCPG, but not with GFP alone, indicatingthat there are at least two regions in CCPG located in N-terminus andC-terminus interacting with PPARγ.

Example 6 The LXXLL Motifs in CCPG are not Required for its Interactionwith PPARγ

LXXLL motif has been thought to mediate ligand-dependent recruitment ofp160-type of coactivator to nuclear receptor (Heery et al. (1997) Nature387, 733-736; McInerney et al. (1998) Genes Dev. 12, 3357-3368).Notably, CCPG has four characteristic LXXLL motifs: one in theN-terminus and three in the C-terminus. The inventor subsequentlyexamined whether the presence of LXXLL motifs in CCPG contributes toCCPG-PPARγ interaction. The inventor generated GFP-tagged CCPG mutantswith a series of mutated LXXLL motifs (LXXLL to LXXAA) (FIG. 5E) andutilized co-IP assay to analyses their interactions with PPARγ. As shownin FIG. 5F, even CCPG mutated with all four LXXLL motifs did notcompromise its binding to PPARγ. Thus, LXXLL motifs of CCPG were notrequired for its interaction with PPARγ, indicating the presence ofnovel structural motif(s) in CCPG responsible for its interaction withPPARγ.

Example 7 N-terminus of CCPG Enhances Transactivation of PPARγ

Knowing that CCPG interacts with PPARγ, the inventor asked whether CCPGtransactivates PPARγ. CCPG and PPARγ were co-expressed in HCT-116 cellswith a consensus PPARγ-responsive luciferase reporter constructPPRE-TK-LUC (Zhu et al. (1996) Gene Expr 6, 185-195; Zhu et al. (1997) JBiol Chem 272, 25500-25506). A previously identified PPARγ coactivatorPGC-1α was used as a positive control (Puigserver et al. (1998) Cell 92,829-839). As indicated in FIG. 6A, CCPG alone did not activate thetranscription of PPRE-TK-LUC, while in the presence of PPARγ and itsligand Tro (1.0 μM), CCPG significantly increased the transactivation ofPPARγ in HCT-116 cells in a degree similar to PGC-11. Interestingly, amoderate synergistic effect on the transactivation of PPARγ was observedwhen CCPG was co-transfected with PGC-1α. However, there was no directinteraction between CCPG and PGC-1α in co-IP assay (data not shown).

Given that N-terminal and C-terminal regions of CCPG are able to bind toPPARγ, the inventor subsequently dissected which region of CCPG mediatedPPARγ transactivation. To avoid the interference of GFP intransactivation reporter assays, the inventor subcloned N-terminal CCPG(1-561) and C-terminal CCPG (562-786) into pcDNA3.1 expression vector.As shown in FIG. 6B, when cotransfected with equal amount of CCPGexpression constructs, the N-terminus (1-561) had slightly higherability to activate PPARγ, as compared with full-length CCPG. Incontrast, C-terminus (562-786) had no ability to coactivate PPARγ andinstead showed a suppressive effect on PPARγ activation. To evaluatewhether either of these CCPG truncates suppresses wild-type CCPGactivity, full-length CCPG was co-transfected with increasing quantitiesof either its N-terminus (1-561) or C-terminus (562-786) of CCPGexpression constructs. Co-expression of CCPG and its N-terminus (1-561)generated synergistic effects on PPARγ transactivation in adose-dependent manner, while co-expression of CCPG and its C-terminus(562-786) resulted in a dose-dependent inhibition of PPARγ activationindicating that the N-terminus of CCPG may have an activation domain(FIG. 6C). To test whether CCPG bears intrinsic transcriptionalactivity, as does by many coactivators such as PGC-1α (Puigserver et al.(1999) Science 286, 1368-1371), CCPG was fused to GAL4 DNA bindingdomain (GAL4 DBD). Transcriptional activity was analyzed through aluciferase reporter containing five GAL binding sites. As shown in FIG.6D, CCPG fused to GAL4 DBD did not activate transcription while a strongtranscriptional activity was seen with GAL4 DBD-fused PGC-1α. Thus, CCPGdoes not possess intrinsic transcriptional activity. Furthermore,cotransfection assay showed that CCPG coactivated PPARγ transactivation(FIG. 6E) when using a native acyl-CoA Oxidase (ACO) PPRE luciferasereporter (Park et al. (2003) Diabetologia 46, 365-377). In addition,ERE-reporter assay also demonstrated that CCPG moderately coactivatesendogenous ERα in MCF-7 cells (FIG. 6F) in a ligand dependent manner.

Example 8 CCPG Promotes Adipogenesis of OP9 Preadipocytes

Given that CCPG augments the transactivation of PPARγ, the inventorinvestigated whether CCPG promotes adipogenesis of OP9 preadipocytes, amodel for adipogenesis (Wolins et al. (2006) J. Lipid Res. 47, 450-460).The inventor initially examined the expression profiles of CCPG andPPARγ in differentiating OP9 cells. OP9 preadipocytes were stimulated toenter an adipocyte differentiation process with an adipogenic mixcocktail, and subjected to time-course sampling (Wolins et al. (2006) J.Lipid Res. 47, 450-460). Two days after reaching confluency (day 0), OP9preadipocytes were transduced with adenoviruses Ad-GFP or Ad-GFP-CCPG (5multiplicity of infection/cell) and cultured in MEM-α plus 10 percentBSA supplemented with or without adipogenic mix cocktail for furtherculture for up to 8 days. The culture media were refreshed every 2 days.At the specified time point, the morphological changes of the cells werephotographed, and the cells were collected either for real-time RT-PCRor northern and western blot analyses. In addition, Oil-Red O stainingwas performed for the accumulated lipids in the adipocytes (Castillo etal. (1999) EMBO J 18, 3676-3687).

As shown by Northern and western blots, CCPG mRNA transcription isup-regulated in OP9 cells starting from day 2 and peaking at day 4during adipogenesis, whereas PPARγ mRNA transcription reached peak onday 2, then declined (FIG. 7A). The protein changes of CCPG had thesimilar pattern as its mRNA and PPARγ was increased until day 6 (FIG.7B). To clarify whether CCPG interacts with endogenous PPARγ indifferentiating OP9 cells, GFP and GFP-tagged CCPG were constructed inan adenovirus expression vector and the resulting viruses (designated asAd-GFP or Ad-GFP-CCPG) were used to transduce OP9 preadipocytessubjected to adipocyte differentiation with stimulation of adipogenicmix cocktail. On adipocyte differentiation day 2, OP9 cells werecollected and subjected to co-IP assay. As showed in FIG. 7C, CCPGinteracts with endogenous PPARγ in differentiating OP9 cells. Theinventor further investigated whether CCPG promotes the adipogenesis ofOP9 preadipocytes. OP9 preadipocytes were transduced with virus Ad-GFPor Ad-GFP-CCPG and then subjected to adipocyte differentiation. To avoidthe overwhelming effects of adipogenesis-induced by high concentrationof cAMP and insulin (Wolins et al. (2006) J. Lipid Res. 47, 450-460),which may overshadow the effects of CCPG, low concentration of exogenousPPAR agonists (Tro, 0.5 μM) and other adipogenic agents such asdexamethasone (0.1 μM) and 3-isobutyl-1-methylxanthine (IBMX, 50 μM)were added to OP9 cell culture medium. As shown in FIG. 8A, OP9preadipocytes transduced with Ad-GFP have very few cells (less than 5percent) showed morphological differentiation towards adipocytes, whileOP9 preadipocytes transduced with Ad-GFP-CCPG had a marked morphologicaldifferentiation into adipocytes at day 4 (more than 90 percent,ascertained by Oil-Red-O staining for lipid deposition). This result wasfurther validated by immunodetection of adipocyte-specific markeradiponectin and perilipin (FIG. 8B).

Example 9 Interference RNA

To evaluate the roles of endogenous CCPG in adipogenesis, CCPGtranscripts were knocked down by adenovirus-delivered RNA interference(RNAi). OP9 preadipocytes were subjected to CCPG RNAi or control LacZRNAi and adipogenesis with adipogenic mix cocktail for 4 days. Real-timeRT-PCR showed that CCPG mRNA was significantly reduced in CCPG RNAitreated cells (FIG. 8C). Meanwhile, the adipocyte differentiation of OP9cells was remarkably compromised in CCPG RNAi1 or CCPG RNAi2-treated OP9cells, but not in LacZ RNAi and CCPG RNAi2 mutation (CCPGRNAi2M)-treated OP9 cells as examined by Oil-Red-O staining (FIG. 8D)and immunodetection of adipocyte-specific marker adiponectin andperilipin (FIG. 8E). Taken together, our data indicate that CCPG is abona fide coactivator and promotes the adipogenic action of PPARγ.

All publications and patents cited in this specification are herebyincorporated by reference in their entirety. The discussion of thereferences herein is intended merely to summarize the assertions made bythe authors and no admission is made that any reference constitutesprior art. Applicants reserve the right to challenge the accuracy andpertinence of the cited references.

1. An isolated nucleotide sequence selected from the group consisting of: a. a sequence which expresses a CCPG polypeptide selected from the group consisting of SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:4, and SEQ ID NO:5; b. a sequence which expresses a polypeptide consisting of residues 1-561 of SEQ ID NO:1; c. a sequence which expresses a polypeptide consisting of residues 562-786 of SEQ ID NO:1; d. a sequence which expresses a polypeptide consisting of residues 1-320 of SEQ ID NO:1; e. a sequence which expresses a polypeptide consisting of residues 420-786 of SEQ ID NO:1; f. a sequence which expresses a CCPG polypeptide of SEQ ID NO:2, g. a sequence which expresses a polypeptide consisting of residues 1-320 of SEQ ID NO:2; h. a sequence which expresses a polypeptide consisting of residues 420-786 of SEQ ID NO:2; i. SEQ ID NO: 7; j. a degenerative variant of SEQ ID NO: 7; k. SEQ ID NO: 6, SEQ ID NO: 8 SEQ ID NO: 9, and SEQ ID NO: 10; and l. degenerative variants of SEQ ID NO: 6, SEQ ID NO: 8 SEQ ID NO: 9, and SEQ ID NO:
 10. 2. The isolated nucleotide sequence of claim 1 whereby the nucleotide sequence expresses a polypeptide having at least 67, 80, 90, or 95 percent identity to any of the CCPG polypeptides of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, and SEQ ID NO:5.
 3. The isolated nucleotide sequence of claim 1 whereby the nucleotide sequence expresses a polypeptide fragment of SEQ ID NO:2, whereby the fragment is selected from the group consisting of residues 1-320, 321-419, 420-786, and 787-910 of SEQ ID NO:2.
 4. The nucleotide sequence of claim 1 wherein the polypeptide contains as many as 50 conservative amino acid substitutions.
 5. The nucleotide sequence of claim 1 wherein at least one of the sequences is incorporated into an expression vector.
 6. The expression vector of claim 5 wherein the expression vector is maintained with in a cell.
 7. The isolated nucleotide sequence of claim 1 further comprising a viral delivery system, wherein the isolated nucleotide is operably incorporated in a viral nucleotide sequence such that when transfected into a mammalian cell the CCPG polypeptide is expressed.
 8. The nucleotide sequence of claim 1 further comprising a reporter.
 9. An isolated nucleotide sequence selected from the group consisting of SEQ ID NO:7 and a degenerative variant of SEQ ID NO:7.
 10. An isolated nucleotide sequence selected from the group consisting of SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:9, and SEQ ID NO:10 and degenerative variants of SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:9, and SEQ ID NO:10.
 11. An isolated RNAi that inhibits expression of a nucleotide sequence encoding a CCPG polypeptide.
 12. The RNAi of claim 11 comprising consecutive nucleotides selected from the group consisting of SEQ ID NO:11, and SEQ ID NO:12.
 13. The RNAi of claim 11 selected from the group consisting of SEQ ID NO:11 and SEQ ID NO:12.
 14. The isolated RNAi of claim 11 further comprising an expression vector.
 15. The isolated RNAi of claim 11 further comprising a viral delivery system, wherein the isolated nucleotide is operably incorporated in the viral nucleotide sequence such that when transfected into a mammalian the CCPG polypeptide is expressed.
 16. An isolated polypeptide which can influence adipogenesis in a cell, the polypeptide selected from the group consisting of: a. SEQ ID NO:1; b. SEQ ID NO:2; c. residues 1-320 of SEQ ID NO:1; d. residues 420-786 of SEQ ID NO:1; e. residues 1-320 of SEQ ID NO:2; f. residues 420-786 of SEQ ID NO:2; g. a fusion protein which includes the polypeptide sequence of a through g; h. a variant of SEQ ID NO:1 with at least 75 percent identical to SEQ ID NO:1; i. a variant of SEQ ID NO:2 with at least 75 percent identical to SEQ ID NO:1; j. antibodies raised against the polypeptides of a through I; and k. antibodies raised against the polypeptides of a through I further comprising a reporter.
 17. The isolated polypeptide of claim 16 containing as many as 50 conservative amino acid substitutions.
 18. An isolated polypeptide of SEQ ID NO:1.
 19. An isolated polypeptide of SEQ ID NO:2.
 20. A method of influencing adipogenesis in a cell comprising a. transfecting a cell with a vector containing a nucleotide sequence selected from one of the sequences of claim 1; b. expressing the nucleotide sequence; and c. producing a polypeptide of claim
 16. 21. A method of identifying compounds with CCPG coactivator or corepressor activity comprising, a. contacting a mammalian cell with a test agent, i. whereby the mammalian cell is transfected with a nucleotide encoding a CCPG polypeptide with PPARγ coactivator or corepressor activity, and a PPARγ reporter, ii. whereby the mammalian cell produces the CCPG polypeptide which activates or represses the PPARγ reporter, iii. whereby the test agent competes with the CCPG polypeptide thereby reducing the CCPG activation or repression of the PPARγ reporter, b. measuring the PPARγ reporter.
 22. The method of identifying compounds with CCPG coactivator or corepressor activity of claim 21 whereby the PPARγ reporter is PPRE-TK-LUC. 